Definitions of the types of behavior falling within the respective purviews of mental health and criminal justice show considerable overlap. For example, the expanded definitions of insanity, while satisfying current understanding of mental illness, pose serious questions about the place of legal responsibility in a free society. However, while the forces that contribute to an individual's behavior can be recognized, the concept of blame may still be necessary, since it is one of the ways in which culture defines the extreme beyond which nonconformity may not go. Research has found that arrest rates, even in combination with recidivism rates, may well be an inadequate criterion in determining the potential for violent behavior among released mental patients. Although psychiatric and psychological diagnosis can predict violence at a better than chance ratio, overprediction is prevalent. Thus, despite society's demand for certainty, the most valid prediction on of violence or dangerousness may be an empirical one based simply on past behavior patterns. Yet rather than establishing priorities for dealing with mentally abnormal offenders (even those potentially dangerous), emphasis has been placed on diversion. Moreover, the mental health system has engaged in deinstitutionalization of hospital populations without buildup of adequate community care programs and facilities. Concurrently, the criminal justice system has concentrated on diversion and community correctional programs as its courts and correctional facilities have become swamped with record numbers of offenders. Yet when the treatment results for mentally abnormal offenders are examined, the conclusion must be that neither system is currently effective in preventing the recurrence of the behavior that brought the individual into the system. Society may agree that some criminals are not insane and that some of the insane are not criminal, but for the great mass of those whose behaviors defy simple classification, there is no established way of coping with or helping them as they are shunted between the two systems. Forty-four references are appended.